1. Field of the Invention
The present invention relates to improved pleural biopsy procedure needles. Such needles are used for obtaining tissue samples of the parietal pleura for biopsy examination purposes and to more easily permitting thoracentesis procedures.
2. Description of Related Art
Two types of needles are and have been widely used for a number of years for obtaining pleural biopsy specimens. One of these is commonly denominated a Cope needle which is comprised of a number of structural pieces collectively shown at 20, in FIG. 1. The Cope biopsy device consists of four parts: an outer cannula 22, a hooked biopsy trocar 24, an interior hollow trocar 26, and a solid innermost obturator or stylet 28. To obtain a pleural biopsy specimen using the Cope needle, stylet 28 is inserted inside hollow trocar 26, which, in turn, is placed inside outer cannula 22. At this point, biopsy trocar 24 is not yet part of the assembled combination. An incision is made in the patient and the assembly of pieces 22, 26 and 28 is then introduced into that incision. Because the distal end of stylet 28 and trocar 26 are both beveled and sharpened, the needle assembly can be pushed through tissue until the distal end lies within the pleural cavity of a patient. Next, stylet 28 is removed from within trocar 26. When this step occurs an opening may be allowed into the pleural cavity. Thereafter, a syringe is removably attached to the proximal end of hollow trocar 26. Connection of a syringe could not occur prior to this as stylet 28 had to be removed. Aspiration of fluid into the newly attached syringe indicates the correct placement or location of the distal end of the assembly consisting of cannula 22 and trocar 26 inside pleural cavity. After aspiration, hollow trocar 26, together with its syringe, is withdrawn and replaced with the hooked biopsy trocar 24, which is also removably connected to a syringe. It may be noted that, during the withdrawal and replacement procedures used on stylet 28, trocar 26 and biopsy trocar 24, the possible opening created by the removal of hollow trocar 26 into the pleural cavity, as noted above, needs to be occluded in order to avoid a leakage of air into pleural cavity. Such leakage can cause pneumothorax, precipitating a respiratory failure.
Following insertion of hooked trocar 24, another aspiration step may be employed to again check for proper positioning of the distal end of trocar 24. The whole assembly, cannula 22 and trocar 24, is rotated about its longitudinal axis until a direction guard 30 on the proximal end of hooked trocar 24 indicates the inferior position of distal hook 32. This position is essentially as shown in FIG. 2. Next, the whole assembly is pulled backwards. Resistance against pulling signifies that hook 32 of trocar 24 has been caught by tissue of the pleura. While hook 32 remains engaged with the pleura tissues, outer cannula 22 is advanced to cut off the hooked piece of pleura tissue. This is shown in FIG. 3. Thereafter, removal of the whole assembly, cannula 22 and trocar 24, along with the severed sample of tissue between the outer cannula 22 and trocar 24, completes the biopsy tissue collection procedure. Only one specimen is collectable.
The other type of biopsy needle is commonly known as the Abram's needle. The Abram's needle also consists of a number of structural elements collectively shown in FIG. 3. The three pieces forming the Abram's needle are an outer trocar 36, having a blunt, closed distal end, an inner, hollow, cutting cannula 38, and an inner, solid stylet 40. Prior to use, all three pieces are assembled with stylet 40 located within cannula 38 and that combination being in turn inserted into outer trocar 36. Following an incision in the patient's chest, the Abram's needle is inserted through the incision into the patient's pleural cavity 154. Following insertion, solid stylet 40 is removed and a syringe is removably attached to the then exposed proximal end of the inner cutting cannula 38. A small quantity of fluid is thereafter aspirated to check for the correct placement of the distal end of the assembly inside pleural cavity. After aspiration, the inner cutting cannula is withdrawn to open and expose a cutting edge on a distal end notch 42 formed in outer trocar 36. Next, outer trocar 36 is pulled rearwardly to catch or engage the pleura on the distal side of notch 42, after which inner cutting cannula 38 is rotatingly advanced to cut off a piece of the engaged pleura. This cutting action is partially shown in FIG. 6. Finally, the whole needle assembly, together with the tissue sample now lodged inside the outer trocar 36 at the distal end of inner cannula 38, is withdrawn from the patient completing the procedure and with a single tissue sample.